The present invention relates to an image reading method for an image recording system which reads an image with an image reader in the form of an array of photoelectric signal converting devices, converts the resulting analog image data into digital image data, and then prints out the digital data with a printer.
There has been extensively used an image recording system which generally comprises an image reader, or scanner, for reading an original document by scanning it in a main scanning and a subscanning direction, an analog-to-digital (A/D) converter for converting the image read into digital data, and a printer for printing out the digital data which may be implemented as a dot printer. The scanner is usually implemented by an array of CCDs (Charge Coupled Devices) or similar photoelectric signal converting devices. In this kind of image recording system, the period of time necessary for the scanner to read one whole line and the period of time necessary for the printer to print out one whole line in dots is synchronous to each other. It follows that the one-line reading time or scanning time of the scanner has to be changed depending upon the printing time which differs from one kind of printer to another. On the other hand, the quantity of light which is to become incident to the CCDs from a lamp such as a fluorescent lamp while the scanner scans an image is predetermined in matching relationship to the one-line scanning time. Hence, in an image recording system with which a plurality of different kinds of printers are usable, the quantity of light to be incident to the CCDs has to be changed every time a printer is changed. This results in the need for special control means for adequately changing the above-mentioned quantity of light every time the printer and therefore one-line printing time is changed, rendering the entire system complicated.